Mysterious Battery Failure

Q1:Is this a coincidence? Prior to my trip to the shop four days ago, I never had any indication that my battery was failing. I had snow tires, rims installed by the local tire store. During the installation they opened the hood and did a 22 point inspection.. unsolicited by me. When the car came off the lift, it would not start. Hmm... the technician said that he did NOT leave the key turned on in the ignition. He also tried to jump start the car... First time that he did that, he connected directly to the battery. It did not turn over. He tried again and got a second battery booster pack and this time at my insistence they jumped it using the correct terminals in the engine bay.

He ran a diagnostic that shows that one cell was bad and readout at 10.2 volts. The battery is OEM, and the 2003 530i has 55,000 miles. Nonetheless, the battery never had shown any sign of failure, slow turns, etc. Q2:Could they have inadvertently discharged it somehow during the lift and/or the inspection? Now the battery needs to be replaced. They were very apologetic and did not charge for the tire switchout or try to upsell me. But I am stuck with a nearly dead battery (barely will turn over) and want to know if they are at fault. Q3: Any reason to buy OEM vs. say Optima vs. Die Hard. Q4: Could they have done additional damage to the computer when they did the first jump start. (When I drove home fuel gauge read empty (I had half a tank)... and the temp gauge said minus 40F. Please advise.

I think it's difficult to assign blame. Maybe your battery just happened to exhibit failure at that moment? Or maybe the shop work was related? Tough call.

On the battery front, I recently replaced my 540i battery with a Bosch unit from Pep Boys. The same group size was available in another brand, but its vent tube was not in a convenient location. The factory battery was at least 2x more expensive and had a much shorter warranty. I don't think Optima makes a compatible battery (I wanted one).

Be very careful replacing, charging, and jumping E39 batteries. It appears a voltage spike occured while I attempted to start my car with a dead battery and jumpers. It took out my Nav player which supposedly isn't unusual. Also, the alternator is sensitive to low batteries. My replacement documenation said low batteries are a common cause of failed alternators. Frankly I've had my fill of late model BMW electronics.

You may want to search the internet for info about your fuel gage and temperature readings. Maybe there's a simple reset or maybe your due for another visit to the dealership

Gone through quite a few batteries on quite a few cars, and every time the failure was just like that: catastrophic. I think I've had a day or so of a warning once, if at all (it may have been my first time and I could be in denial, trying to jump start it and hoping to recharge).

I have a 2002 E39 540 which had the original battery for almost 8 years and 140K miles. One morning the car would start so I replaced the battery with one from Sears. Unfortunately, the problem has not gone away. I now have to jump start the car most mornings. I took the car to my mechanic and he tested the battery and alternator, which seemed normal. We put a disharge meter on the battery and after 4 minutes of the car being off, the discharge settles in at .39 miliamps. We went through a proceedure in which we pulled every fuse and monitored the meter reading. The only change to the .39 reading was when we pulled fuse #9 which was for the climate control and headlight washers. With this fuse pulled the battery discharge dropped to .15 miliamps. After I left the shop, I drove for an hour to give the battery a full charge. I put he car back in the garage, pulled fuse #9 and made sure every thing was off. The next morning the battery did not have enough juice to start the car. Any suggestions where to look next would be greatly appreciated.

Actually, the reading was 39 mA, not 0.39, and is actually a little below normal, 50-60 mA is typical.

If you have a DMM, check the battery voltage after the car sets overnight, with the trunk open. S/b at least 12.5. Of much lower, the battery is dying.

Run the engine at 1000 RPM. The battery voltage s/b 13.5- 14.5 V. If lower, the alt is not putting out enough current.

How many miles is your daily commute? If 10 mi or less, and the heat and rear window defogger are on during the drive, the car is not being driven long enough to keep the battery up. You may need to buy a smart battery charger, and run it every night.

On the topic of cabin fan and FSR and a dead battery... it was a hit or miss kind of thing.
No real prediction to when the battery would be dead. VERY FRUSTRATING!!!
After changing the FSR, battery has been fine.

Just replaced the bad battery. All is well for now, I shall know tomorrow morning after an overnight cold soak at 50ÃƒÆ’Ã†â€™ÃƒÂ¢Ã¢â€šÂ¬Ã…Â¡ÃƒÆ’Ã¢â‚¬Å¡Ãƒâ€šÃ‚ÂºF. My gas guage is reading correctly now. I thought someone had siphoned off some gas last night

Would any of you recommend replacing the Final Stage Resistor? I've seen it mentioned here in relation to overnight battery discharge.

I will need to eventually install a battery switch or some type of protection to prevent excessive discharge of the battery when left unattended. I will probably need to leave the car parked for 3 day weekends while I travel home in the near future.

Why have all car manufacturers (that I know of) eliminated battery voltage as an instrument on the panel?

On the topic of FSR (final stage resistor) for a dead morning battery......

One of the easiest ways to determine if it needs replacing is to disconnet the electrical plug to it while leaving the unit in place.
You will not have a cabin fan, but if the culprit is the FSR, the battery will not discharge.

Said another way, after disconnecting the FSR and your battery goes dead, then LIKELY not the FSR.